
// 定义飞机类
function Plane(src,w,h,x,y){
    Sprite.call(this,src,w,h,x,y)
}
Plane.prototype = new Sprite;

Plane.prototype.move = function(x,y){
  this.imgNode.style.left = x - 50 + 'px';
  this.imgNode.style.top = y - 40 + 'px';
  this.x = this.imgNode.offsetLeft;
  this.y = this.imgNode.offsetTop;
}
